Mature follow-up of Low-dose rate interstitial brachytherapy following ipsilateral breast tumor recurrence in patients initially treated with breast conservation therapy

Abstract

Objective: To evaluate our mature follow-up data in women who have developed IBTR following conservation surgeryand post-operative external radiotherapy retreated by lumpectomy followed by interstitial brachytherapy in lieu of salvagemastectomy.Methods: Between 1/1998 and 10/2006, twenty-two patients with TIS or T1 IBTR were offered interstitial low-dose ratebrachytherapy following tumor re-excision as an alternative to salvage mastectomy. All patients had failed lumpectomyfollowed by standard postoperative external beam radiotherapy (range 5000-6480cGy). The recurrent tumors were excisedwith final margins of resection free of residual disease. Tumor bed implantation was then carried out with an interstitialtechnique utilizing 192Iridium with the target volume consisting of the tumor bed plus a minimum 1.0 centimeter margin(minimum standard dose 4500cGy).Results: With a mean follow up of 67.5 months (range 17-115 months) Twenty-one of 22 patients maintained localcontrol at the time of last follow-up or at the time of their death. The single patient who developed a second localrecurrence was treated successfully with mastectomy. Three patients succumbed to systemic disease. Two patientsdeveloped localized skin breakdown. One patient developed a contralateral breast cancer. Long-term cosmetic results asdefined by the Harvard cosmesis scale and the Allegheny General modification were acceptable.Conclusions: These long-term data suggest that lumpectomy followed by brachytherapy is feasible and may be anacceptable alternative to salvage mastectomy in patients who locally fail conservation breast therapy. The upcomingRTOG retreatment trial (RTOG 1014) should help define the role of repeat conservation therapy in IBTR.